Bio - The fight-or-flight response Flashcards
What is the response to a threatening or stressful situation known as?
The fight-or-flight response.
What are some reactions of the body caused by the fight or flight response?
Faster heartbeat, breathing rate increases, muscles tense.
When an individual is faced with a threat, what area of the brain becomes mobilised?
The amygdala.
When does the amygdala become mobilised?
When an individual is faced with a threat.
What is the fight-or-flight response to?
Stress.
What does the amygdala do?
Associates sensory signals (what we see, hear or smell) with emotions associated with fight or flight, such as fear or anger.
It then sends a distress signal to the hypothalamus, which functions like a command centre in the brain, communicating with the rest of the body through the sympathetic nervous system.
What systems does the body’s response to stressors involve?
One for acute (i.e. sudden) stressors such as personal attack.
One for chronic (i.e. ongoing) stressors such as a stressful job.
When the sympathetic nervous system (SNS) is triggered in the response to acute stressors, what does it do?
Begins the process of preparing the body for the rapid action necessary for fight or flight.
The SNS sends a signal through to the adrenal medulla, which responds by releasing adrenaline into the bloodstream.
What sends the signal to the adrenal medulla to release adrenaline in the response to acute stressors?
The SNS.
What physiological changes does adrenaline cause as it circulates through the body?
Heart beats faster, pushing blood to the muscles, heart and other vital organs, and blood pressure increases. Breathing becomes more rapid in order to take in as much oxygen as possible with each breath.
Adrenaline also triggers the release of blood sugar (glucose) and fats, which flood into the bloodstream, supplying energy to parts of the body associated with the fight or flight response.
What system is activated once the stressors have passed in the response to acute stressors?
Parasympathetic nervous system.
What does the parasympathetic system do?
Slows down the heartbeat again and reduces blood pressure. Digestion (which was inhibited by the SNS) begins again.
What does the HPA axis consist of?
The hypothalamus, pituitary gland and the adrenal gland.
What stress response is triggered if the brain continues to perceive something as threatening?
Response to chronic stressors.
When is the response to chronic stressors activated?
If the brain continues to perceive something as threatening.
Explain the H in HPA axis
The hypothalamus.
The HPA axis relies on a series of hormonal signals to keep the SNS working. In response to continued threat, the hypothalamus releases the chemical messenger corticotropin-releasing hormone (CRH), which is released into the bloodstream in response to the stressor.
Explain the P in HPA axis
The pituitary gland.
When CRH arrives at the pituitary gland, it causes the pituitary gland to produce and release adrenocorticotropic hormone (ACTH). This is then transported in the bloodstream to its target site in the adrenal glands.
Explain the A in HPA axis
The adrenal glands.
ACTH stimulates the adrenal cortex to release various stress-related hormones, including cortisol. Cortisol is responsible for several effects that are important in the fight or flight response. Some positive (quick burst of energy and lower sensitivity to pain), some negative (impaired cognitive performance and lowered immune system).
A response to which type of stressor involves feedback?
Chronic stressors.
Explain the feedback used in the response to chronic stressors.
Both the hypothalamus and pituitary glands have receptors on them that monitor circulating cortisol levels. If these rise above normal, they initiate a reduction in CRH and ACTH levels, thus bringing cortisol levels back to normal.
What is the fight-or-flight response?
A sequence of activity within the body that is triggered when the body prepares itself for defending or attacking (fight) or running away to safety (flight).
This activity involves the changes in the nervous system and the secretion of hormones that are necessary to sustain arousal.
What is the HPA axis?
Describes the sequence of bodily activity in response to stress that involves the hypothalamus, pituitary gland and adrenal cortex.
